The present invention relates generally to photosensing optical signals, and more particularly to photosensing photon energies of optical signals with photosensor arrays on integrated circuits (ICs).
U.S. Pat. No. 5,166,755 describes a spectrometer apparatus in which a spectrum resolving sensor contains an opto-electronic monolithic array of photosensitive elements and a continuous variable optical filter. The filter can include a variable thickness coating formed into a wedge shape on a substrate or directly on the surface of the array. If polychromatic light, such as light reflected from a sample or a strip of a scene viewed from a spacecraft, passes through the variable filter and is spectrally resolved before incidence on the array, the output of all the elements in the array provides the spectral contents of the polychromatic light. High spectral resolving power is obtained by subtracting the output signals of adjacent elements in the array.
U.S. Pat. No. 5,166,755 mentions many applications. Non-imaging applications include measurement of spectral transmission through samples; for molecular absorption and emission spectra; for spectral reflectance measurements; for pollution and emission control by measuring transmission or absorption; for astronomical spectral analyses of stellar radiation; for pyrometry by measuring thermal radiation; and underwater spectrometry. Imaging applications include color copying machines; color printing; color facsimile machines; color picture-phone; color page scanning; robotic vision; aerial mapping; air-borne and space-borne resources monitoring; reconnaissance and surveillance; sorting of items; non-contact inspection; missile guidance; and star tracking.
It would be advantageous to have improved techniques for photosensing optical signals with ICs.